The invention relates to a universal joint arrangement for the interconnection of an apparatus holder or an apparatus holder mounting plate or a similar device and a support arm or a support console.
Mobile apparatus such as minicomputers, so-called PDA's (Personal Digital Assistants) navigation apparatus, mobile telephones and similar apparatus are used in motor vehicles, on desks or at other locations in connection with apparatus carriers which include a console or a support arm, to which an apparatus holder or a mounting plate for supporting an apparatus holder is connected by way of a joint structure so that the respective apparatus can be adjusted to a position which is convenient for the observation of the visual display of the apparatus and for the operation of the apparatus.
Universal joints for that purpose are known in the form of two adjacent hinge joints oriented so as to be pivotable in rectangularly displaced planes and also in the form of ball joints with spherical segment-shaped joint parts. In order to hold a particular apparatus stable in a selected position, it is of course necessary that the joint mechanism can be locked or that it is pretensioned so as to provide for sufficient friction between the joint parts to hold the joint parts in a particular selected position. In known ball joint mechanisms, the required clamping tension is generated in that a screw is screwed from the mounting plate that is from the side of the apparatus into the seating area of the joint mechanism and tightened to the degree needed to engage the joint parts. However, since the joint parts all consist essentially of plastic material which has a heat expansion coefficient different from the engagement means substantial problems have been encountered particularly in connection with the use of such joints in motor vehicles because of the high temperature changes for example as a result of the heating of vehicles parked in the summertime in the sun. Then, it has been found that the clamping tension becomes so relaxed that the apparatus holder will no longer maintain the adjusted position. This can be not only very annoying because it makes the use of the apparatus difficult but also because the necessary tensioning can be performed only with the use of a fitting screw driver and this process is often possible only by the removal of the apparatus holder or even additionally the mounting plate. Furthermore, upon cool-down, the joint may be so tight that it can no longer be adjusted.
It is therefore the object of the present invention to provide an arrangement by which the problem described above can be controlled easily and without complicated design features.